local bit32 = require("bit32")

-- going clockwise direction is 1 for 12 oclock 2 for 3, 3 for 6 and 4 for 9
local direction = 1

term.clear()
term.setCursorPos(0, 0)
print("Welcome to HilbertTurtle the turtle mining program which uses a sudo HilbertCurve")
print("Please input an order for the hilbert curve:")

local order = io.read()
print("Please input a thickness between tunnels:")
local thick = io.read()
local N = 2^order
local total = N*N
local volume = total*(thick*2)
local pathX = {}
local pathY = {}

print("Thank you, Estimate blocks mined is: " .. volume)

local function digforward(num)
    local k = num
    for i = 1, k, 1 do
        while turtle.detect() == true do
            turtle.dig()
        end
        turtle.forward()
        turtle.digDown()
    end
end

local function turnTo(targetDir)
    local tDir = targetDir
    while direction ~= tDir do
        turtle.turnRight()
        direction = direction + 1
        if direction > 4 then
            direction = 1
        end
    end
end

local function goTo(x,y,u,v)
    local xx = x
    local yy = y
    local uu = u
    local vv = v
    local targetDir
    if uu > xx then
        targetDir = 2
    elseif uu < xx then
        targetDir = 4
    elseif vv > yy then
        targetDir = 1
    elseif vv < yy then
        targetDir = 3
    end
    if direction ~= targetDir then
        turnTo(targetDir)
    end

    local num = (math.abs(xx - uu)) + (math.abs(yy - vv))
    digforward(num)
end

local function hilbert(k)
    local i = k
    local pointsX = {0,0,1,1}
    local pointsY = {0,1,1,0}
    local index = bit32.band(i,3)
    local vx = pointsX[index+1]
    local vy = pointsY[index+1]

    for j = 1, order, 1 do
        i = bit32.rshift(i,2)
        index = bit32.band(i,3)

        local len = 2^j
        if  index == 0 then
            local tmp = vx
            vx = vy
            vy = tmp
        elseif index == 1 then
            vy = vy + len
        elseif index == 2 then
            vx = vx + len
            vy = vy + len
        else
            local tmp = len - 1 - vx
            vx = len - 1 - vy
            vy = tmp
            vx = vx + len
        end
    end

    return vx,vy
end

local function createPoints()
    for i = 0, total, 1 do
        local path = table.pack(hilbert(i))
        pathX[i+1] = path[1]
        pathY[i+1] = path[2]
        local len = thick
        pathX[i+1] = pathX[i+1] * len
        pathY[i+1] = pathY[i+1] * len
    end
end

createPoints()

for i = 1, total, 1 do
    goTo(pathX[i],pathY[i],pathX[i+1],pathY[i+1])
end